1. Field of the Invention
This invention relates to polyamides. In one aspect, the invention relates to substantially linear polyamides prepared from N-alkylamide-substituted amines while in another aspect, the invention relates to a process for preparing these polyamides in the presence of aqueous ammonia.
2. Description of the Prior Art
Matlack, U.S. Pat. No. 2,672,480, and Breslow, U.S. Pat. No. 2,749,331, teach the preparation of synthetic, substantially linear polyamides, such as poly-.beta.-alanine, by contacting an amide containing at least one activated ethylene double bond and an active hydrogen atom, such as acrylamide, with a strongly basic catalyst, such as an alkali metal hydroxide, under substantially anhydrous conditions. Wexler, U.S. Pat. No. 3,422,081, extends this process to preparing highly crystalline, substantially linear, stereoregular polymers of methacrylamide by polymerizing the monomer in the presence of a catalyst system comprising a combination of an alkali metal alkoxide and a polyvalent metal salt.
Other methods for preparing polyamides are also known. Hill, U.S. Pat. No. 2,274,831, teaches the manufacture of polyamides by polymerizing amino acids containing as a heteroatom a tertiary amino nitrogen or by reacting diamines and dibasic acids, either or both of which contain a heteroatom of tertiary amino nitrogen. These reactants can form interpolyamides with other materials, such as 6-aminocaproic acid. Graf et al, U.S. Pat. No. 3,093,618, teach a method for the manufacture of polyamides derived from .alpha.-aminocarboxylic acids where the monomer is polymerized at an elevated temperature and preferably in the presence of an accelerator, such as dimethyl formamide. Both Kobayashi et al, U.S. Pat. No. 3,499,879, and Volker et al, U.S. Pat. No. 3,629,203, teach an aqueous process for preparing a polyamide from acrylonitrile. Still other methods for preparing polyamides are known.